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   Driving advice systems in main line operation  evaluated  
Driving advice systems are on-board tools giving recommendations to drivers for a more energy efficient driving style. In main line operation, rather sophisticated algorithms taking into account a number of track and vehicle characteristics exist to continuously calculate the optimum driving pattern for the remaining route.
Technology field: Energy efficient driving
close main section General information
  close sub-section Description
    (no details available)
close main section General criteria
  close sub-section Status of development: test series
   

Various European railways have tested driving advice systems.

  • At Dutch NS prototypes have been developed by NedTrain Consulting in 1996 and were tested in regular passenger service for two years.
  • German DB runs a pilot on the ICE 1 and 2 using a DAS developed in co-operation with Hannover University.
  Time horizon for broad application: 5 - 10 years
    (no details available)
  Expected technological development: highly dynamic
   

Systemic optimisation

Future driving advice systems could integrate a link to the control centre and thus take into consideration unscheduled stops arising from the traffic situation. This would require some communication channel between the DAS and the control centre as well as a corresponding IT support at the control centre.

Extended functionalities

Future driving advice systems could go far beyond giving driving recommendations and offer a wide range of functionalities such as monitoring for maintenance processes and accident investigation etc.

    Motivation:
    Energy saving.
  Benefits (other than environmental): big
   

Punctuality

In-service testing in different systems have shown clear improvements in punctuality.

Capacity

DAS could help drivers to stay inside their infrastructure slot at all times. This would improve slot management and thus increase capacity.

Wear

Coasting instead of braking reduces the wear of the brakes especially if electric braking is not possible.

Passenger comfort

Small improvements in passenger comfort can be achieved through smoother driving. In addition, early train arrival often leading to trains waiting outside stations (a situation hardly comprehensible for passengers) is ruled out by DAS.

  Barriers: medium
   

Availability of digital infrastructure data

For a system-wide introduction of DAS-based energy efficient driving, infrastructure data have to be supplied in a digital form, containing the exact position of stops, junctions, curves and curve radii, slopes etc. In most railway companies these data are only available on paper. Digital version may be obtained by different methods:

  • Manual data conversion: This method is very liable to mistake and proved insufficient at DB AG (for the ESF project, cf. Example)
  • Laser scanning of infrastructure: A special vehicle with a mounted laser scanner “scans” the whole infrastructure. This method is very expensive (~ 2 million EURO for a country like Germany, France or Spain)
  • GPS scanning of infrastructure: This method is cheaper and was applied in Austria. However the result is less accurate compared to laser scanning.

The digitalisation of infrastructure data is one of the principal bottlenecks for the implementation of DAS systems in countries with a big railway network. In smaller railways like SBB, a manual route-by-route approach is feasible.

Updating of track information

For the effectiveness and reliability of DAS recommendations, up-to-date information on track conditions are crucial. If static track and timetable information is used, temporary low-speed sections are not taken into consideration and may lead to DAS causing additional delays. Dynamic information could be supplied via an automatic update at stations (e.g. by a W-LAN link) or via continuous updating by GSM (or other). At DB AG it is planned to make use of the new electronic timetable method (EBuLa) as a data basis for the driving advice system ESF (cf. Example).

Acceptance by drivers and management

Some drivers will be reluctant to follow the recommendations of a DAS for several reasons:

  • If drivers experience train delays caused by insufficient or wrong infrastructure information in the DAS (e.g. temporary low-speed sections), they will no longer follow the system’s recommendations.
  • Some drivers may experience DAS as a step towards automatic train control and therefore as a step towards losing their jobs.
  • If drivers are not intensively familiarised with the DAS, many will not understand the system and will take the recommendations as irrelevant additional information.

Some decision makers think that acceptance by drivers puts too much uncertainty to the effectiveness and thus payback of the system.

Delayed trains

The effectiveness of the system is reduced if train punctuality in the network is low, since the DAS has no effect in this case.

Unexpected stops

If unexpected stops due to red signals occur on the trip, the DAS can no longer operate or may even lead to additional delays. This cannot be avoided even by up-to-date track data, but would require a permanent link to the control centre being a future upgrade of DAS.

Computing power

DAS being a real-time-application, limitations of computing power installed on-board may pose a problem in some cases.

    Success factors:
   

Time buffers

A pre-condition for the use of DAS is the existence of time buffers in the timetable. The saving effect of DAS is the higher, the bigger these time buffers are.

Winning drivers’ acceptance

  • Special training programmes have to be given to drivers
  • Communication of the new system should focus on the purely advisory character of the system and stress that the system supports drivers to fulfil their core task being punctuality.
  • Human-machine interface has to be optimised and the information has to be presented in a clear and functional manner.

Integration into existing ICT infrastructure

When developing or introducing a DAS, synergy effects with existing hardware platforms as well as positioning and data supply systems should be sought in order to reduce costs and overall system complexity.

International standard

An international standard for DAS could create scale effects for the development and introduction of such systems. Furthermore, synergy effects with other international systems such as ETCS can be ensured at an early stage. A UIC project aiming at the definition of standard requirements for energy meters and DAS was finalised in 2002.

  Applicability for railway segments: high
    Type of traction:  electric - DC, electric - AC, diesel
    Type of transportation:  passenger - main lines, passenger - high speed, passenger - regional lines
    The present evaluation focuses on driving advice systems in main line operation. For application of DAS in other fields, cf. DAS for suburban operation and DAS for freight operation.
    Grade of diffusion into railway markets:
  Diffusion into relevant segment of fleet: < 5%
  Share of newly purchased stock: < 20%
    Application is presently limited to pilot projects.
  Market potential (railways): high
    In long term perspective, the market for DAS in main line operation is very high. However, the experience from DB AG or NS Reizigers show that there are many hurdles on the way to a system-wide rollout.
    Example:
   

German driving advice system ESF

In co-operation with Hannover University, German DB AG developed a driving advice system called ESF (Energiesparende Fahrweise). The system gives coasting advices based on track and train data, timetable, position and time. Continuous speed optimisation could also be given by ESF but is presently not activated. The savings to be realised strongly depend on timetable, operational situation and degree of energy efficient driving previously realised by drivers’ skill. An average saving potential of over 5 % on German ICE has been confirmed by tests and calculations. A pilot on ICE 1 and 2 was realised in 2001. At the end of 2002 ESF is planned to start in all ICEs running on lines where the new electronic timetable method EbuLA has been successfully implemented. Exact structure data of the entire network is needed in a reliable and convenient digital version in order to successfully run both EbuLa and ESF. This is the main reason for these systems being restricted to only part of the network in the initial phase.

close main section Environmental criteria
  close sub-section Impacts on energy efficiency:
  Energy efficiency potential for single vehicle: 5 - 10%
  Energy efficiency potential throughout fleet: 2 - 5%
   

Comparing a DAS guided driving strategy with a shortest time driving strategy one gets the theoretical saving potential. For typical time buffers and running patterns, it lies over 20 % in main line operation.

The real saving potential is however considerably lower, for three reasons:

  • Even without DAS drivers do not pursue a shortest time driving strategy, but use a more energy efficient driving style according to their experience, skill and motivation. If there are no delays this may cut energy consumption by 20%.
  • Due to delays the DAS often cannot be used. This may well be the case for about 50% of the trips.
  • Purely advisory character of the system: Some drivers may ignore the advice.

Taking these factors into account, the remaining potential in main line transport lies between 5 and 10%. In individual favourable situations this value can even reach 15%.

ESF test runs at DB AG

Simulations and test runs with ESF on the ICE at DB AG yielded the following results:

  • The theoretical saving potential is 21,2 %.
  • Taking into account that drivers exploit some of this potential without a DAS, the remaining potential is 14,9%.
  • If train delays are also taken into consideration, the average savings are about 7,5 %.

Economymeter test runs at NS Reizigers

In-service testing during two years in the Netherlands has yielded an overall reduction of 6 – 7 %. The reason for this value which is much lower than the theoretical potential are delayed trains and drivers ignoring the driving recommendations.

  Other environmental impacts: neutral
    (no details available)
close main section Economic criteria
  close sub-section Vehicle - fix costs: low
    The on-board hardware is generally cheap, especially if synergy effects with existing hardware (display etc) are used. Main cost factors are the digitalisation of track data and the software development.
  Vehicle - running costs: significant reduction
    If an automated and radio based data supply and updating is in place, additional operating costs are almost negligible.
  Infrastructure - fix costs: low
    There are generally no major infrastructure measures needed. However, a data supply infrastructure to update on-board data is required.
  Infrastructure - running costs: unchanged
    (no details available)
  Scale effects: low
    (no details available)
  Amortisation: 2 - 5 years
    (no details available)
no data available Application outside railway sector (this technology is railway specific)
close main section Overall rating
  close sub-section Overall potential: very promising
  Time horizon: mid-term
    Driving advice systems for main line operation exist and have proven to be operable in in-service testing in several countries. Energy savings are lower than theoretically predicted but still high. Many operators are currently considering a system-wide introduction. The main technical barrier is the compilation of digital track data. Other obstacles are scepticism about the effectiveness and payback of the system as well as uncertainties about the acceptance by drivers. In view of the fact that DAS are among the most effective technological measures to reduce the fleet-wide energy consumption in mid-term perspective, strong efforts should be made to overcome remaining barriers. In long-term perspective, the integration of traffic situation into DAS algorithms could yield further efficiency gains.
References / Links:  Sanftleben et al. 2001;  Voß, Sanftleben 1998;  Linder 2000;  Meyer et al. 2002
Attachments:
Related projects:  Economy Meter;  Ecodriving;  ESF
Contact persons:
 date created: 2002-10-09
 
© UIC - International Union of Railways 2003